The invention relates to a fuel injection pump for internal combustion engines of the type having a cam operated piston element with a control collar surrounded by an adjustable control sleeve for controlling the rotational position of the piston element.
A fuel injection pump of this type is disclosed in German Published Unexamined Patent Application (DE-OS) No. 26 46 546 wherein an element piston is guided in an element sleeve that is provided with a control edge control means and that, at its piston segment projecting out of the element sleeve, has a collar with flattened areas that can be slid in axial direction but is guided in a torsionally fixed way in a control sleeve.
The control sleeve that can be operated by a control rod is disposed so that it turns on the element sleeve and, in the case of a change of load, via the flattened collar, adjusts the element Piston for the purpose of controlling the start of delivery and the delivery rate.
In the case of constructions of this type, the plays caused by manufacturing tolerances between the control sleeve and the collar or so-called element piston lug cause considerable variations of the injected amount that may result in "shaking during idling" and reinforce "urging."
Objectives of the invention are the elimination of the described disadvantages by simple measures that are also advantageous with respect to assembly and are suitable for large-scale production.
These objectives are achieved according to the invention by providing a resilient clamping connection between the control sleeve and the piston control collar. In certain embodiments a separate resilient clamp is interposed between the control collar and the control sleeve. In other preferred embodiments, the control sleeve itself is slotted to form a resilient clamping section. In both cases, the play is eliminated between the element piston and the control sleeve. The measures taken according to the invention for eliminating the play are cost effective and easy to achieve with respect to manufacturing techniques so that they are very well suited for series production.
In one preferred embodiment, the element piston is manufactured as Previously. The control sleeve is only designed to be slotted and subsequently is pressed together by a small amount in such a way that, before the mounting, an elastic overlapping exists between the clear width of the control sleeve and the flattened collar of the element piston.
In the other preferred embodiment, one of the two flattened areas at the collar of the element piston is ground off more, an elastic clamp being inserted between said flattened area and the oppsite side of the control sleeve.
Both embodiments are made to be without Play in the most simple ways. Variations will no longer occur in the characteristic diagram of the injected amount.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.